KR20030023488A - Silicon semiconductor substrate and preparation thereof - Google Patents

Abstract

PURPOSE: To provide a silicon semiconductor substrate having structure which has an oxide deposition defect being a gettering site with high density with the defect-free region of void system crystal right under it, and to provide a method for manufacturing the same. CONSTITUTION: A substrate is obtained through heat treatment of the silicon semiconductor substrate obtained by silicon monocrystal grown by Czochralski method. When setting the defect-free region of an oxide deposition crystal defect to be Oi DZ and a region free from the void system defect of a size >=0.11 μm to be COP DZ, the relation (Oi DZ)-(COP DZ)<=10 μm is satisfied and the oxide deposition crystal defects number >=5x10¬8/cm¬3 in the silicon semiconductor substrate. The silicon semiconductor substrate is obtained from silicon single crystal grown by Czochralski method by using silicon melt containing nitride >=5x10¬7 atoms/cm¬3 and <=5x10¬19 atoms/cm¬3. The manufacturing method performs the heat treatment of the silicon semiconductor substrate in a non-oxidizing atmosphere for not shorter than one hour at a maximum temperature >=1,150°C.

Description

Silicon semiconductor substrate and preparation method thereof

The present invention relates to a silicon semiconductor substrate and a method of manufacturing the same.

Specifically, the present invention relates to a silicon semiconductor substrate having a large gettering layer directly under a defect-free region of a void-based product and a method of manufacturing the same.

Conventionally, in order to improve the gettering effect of a semiconductor substrate, in the silicon wafer detached from the silicon single crystal pulled by the Czochralski method, the interstitial oxygen concentration of the surface layer portion of the mirror surface is 2 × 10 ¹⁷ atoms / cm ³ or less On the mirror surface, a defect-free layer with a depth of 10 µm or more is formed, and the density of micro defects such as oxygen precipitates of the defect-free layer is 10 ⁵ / cm ³ or less, and in the region deeper than the defect-free layer, A silicon wafer is known which has an internal gettering layer in which at least 10 ⁸ defects / cm ³ are formed and does not have an external gettering layer on the back side of the mirror surface (Japanese Patent Laid-Open No. 6-252154).

On the other hand, a silicon single crystal wafer obtained by slicing silicon single crystals grown by doping nitrogen by the Czochralski method, which has improved both a void-free defect-free layer and a gettering effect. A silicon single crystal wafer characterized in that the depth of the defect-free layer is 2 to 12 µm after the gettering heat treatment or the device fabrication heat treatment of the single crystal wafer, and its internal defect density is 1 x 10 ⁸ to 2 x 10 ¹⁰ pieces / cm ³ . Is known (Japanese Patent Laid-Open No. 2000-211995).

However, the former (invention) has no suggestion regarding the addition of nitrogen, and has no suggestion at all about the defect-free layer of void defects. On the other hand, the latter (invention) controls the depth at the surface of the void crystal defects and oxygen oxide defects together, the cooling rate when passing through the temperature range of 1100 ℃ during nitrogen concentration and silicon single crystal traction (hereinafter described only cooling rate) There is no suggestion for the optimization of).

That is, according to the prior art, in order to deepen the defect-free region depth of void crystal defects, annealing operation time is extended for a long time or annealing temperature is increased, but in this case, outward diffusion of oxygen is enhanced and oxygen The defect-free area width of the precipitate became deeper, and the oxygen precipitates also dissolved, thereby weakening the gettering effect.

Accordingly, it is an object of the present invention to provide a novel silicon semiconductor substrate and a method of manufacturing the same.

It is still another object of the present invention to provide a silicon semiconductor substrate having a structure having a high density of oxygen precipitate defects, which become a gettering site, directly below the defect-free region of the void-based crystal, and a method of manufacturing the same.

The above object is achieved by the following (1) to (6).

(1) In a substrate on which a silicon semiconductor substrate obtained from a silicon single crystal grown by the Czochralski method or the magnetic field-applied Czochralski method is heat-treated, the defect-free region of the oxygen precipitate crystal defect is defined as Oi DZ and has a size of 0.11 mu m or more. When the area without void type defect is set to COP DZ,

(Formula 4)

(Oi DZ)-(COP DZ) 10 μm

A silicon semiconductor substrate satisfying the relational formula and having an oxygen precipitate crystal defect of 5 × 10 ⁸ holes / cm ³ or more.

(2) Said (1) characterized in that it has a local enrichment part by nitrogen segregation which shows the signal intensity of 2 times or more of the average signal intensity in nitrogen analysis by secondary ion mass spectrometry (SIMS) at a depth of 5 micrometers or more from the surface (1) A method for producing a silicon semiconductor substrate according to the formula.

(3) A silicon semiconductor substrate having a nitrogen concentration of 5 × 10 ¹⁴ atoms / cm ³ or more and 1 × 10 ¹⁶ atoms / cm ³ or less is subjected to heat treatment in a non-oxidizing atmosphere, and then the oxygen concentration is 7 × at the surface of the substrate center. It is 10 ¹⁶ atoms / cm ³ and has a localized thickening part by nitrogen segregation which shows a signal intensity of 2 times or more the average signal intensity in nitrogen analysis by secondary ion mass spectrometry (SIMS) at a depth of 5 µm or more at the surface. The method for producing a silicon semiconductor substrate according to the above (1).

(4) Obtained from silicon single crystals grown by Czochralski method or magnetic field applied Czochralski method using silicon melt containing 5 × 10 ¹⁷ atoms / cm ³ or more and 1.5 × 10 ¹⁹ atoms / cm ³ or less The silicon semiconductor substrate is heat-treated in a non-oxidizing atmosphere for at least 1 hour at a temperature of at least 1150 ° C. to reach an oxygen concentration of 1 μm deep at the surface at the center of the substrate, and at most 7 × 10 ¹⁶ atoms / cm ³ . The silicon semiconductor substrate according to the above (1), wherein the silicon semiconductor substrate has a local concentration portion by nitrogen segregation that exhibits a signal intensity of at least twice the average signal intensity in nitrogen analysis by secondary ion mass spectrometry (SIMS) at a depth of 5 µm. Manufacturing method.

(5) Cooling rate during traction by the Czochralski method or the magnetic field or Czochralski method using a silicon melt containing 5 × 10 ¹⁷ atoms / cm ³ or more and 1.5 × 10 ¹⁹ atoms / cm ³ or less When the maximum void volume grown at 5 ° C / min or more is the nitrogen concentration of the silicon substrate before heat treatment at Natoms / cm ³ and the cooling rate at the time of traction is CR ° C / min,

(Formula 5)

8620000 × (CR) ^-1.4 × EXP (-3.3E-15 × [N]) 100000 nm ³

The silicon semiconductor substrate according to the above formula (1), wherein the silicon semiconductor substrate obtained at the cooling rate and the nitrogen concentration satisfying the relational expression is heat treated in a non-oxidizing atmosphere for at least 1 hour at a temperature of at least 1150 ° C. Manufacturing method.

(6) Cooling rate during traction by the Czochralski method or the magnetic field or Czochralski method using silicon melt containing 1 × 10 ¹⁸ atoms / cm ³ or more and 1.5 × 10 ¹⁹ atoms / cm ³ or less When the maximum void volume grown at 1 ° C / min or less but less than 5 ° C / min is the nitrogen concentration of the silicon substrate before heat treatment at Natoms / cm ³ and the cooling rate at the time of traction is CR ° C / min,

(Formula 6)

8620000 × (CR) ^-1.4 × EXP (-3.3E-15 × [N]) 150000 nm ³

Manufacture of a silicon semiconductor substrate according to the above formula (1), wherein the silicon semiconductor substrate obtained at a cooling rate and nitrogen concentration satisfying the relational expression is heat treated at a temperature of at least 1200 ° C. for at least 1 hour in a non-oxidizing atmosphere. Way.

The silicon semiconductor substrate according to the present invention is a silicon single crystal rod grown by a Czochralski method (hereinafter referred to as "CZ method") or a magnetic field or Czochralski method (hereinafter referred to as "magnetic field CZ method"). It is obtained by slicing to a thickness.

In other words, the CZ method is a method in which a seed crystal is connected to a melt of a single crystal silicon raw material contained in a quartz crucible, and gradually pulled while rotating it to grow a silicon single crystal rod of a predetermined diameter. Nitrogen can be doped into the traction crystal by adding nitride or by setting the atmosphere gas to an atmosphere containing nitrogen.

In this case, the doping amount of the crystal can be controlled by adjusting the amount of nitride, the temperature of nitrogen gas or the introduction time. The magnetic field or the CZ method is also the same as the CZ method except that the magnetic field is applied in the quartz crucible. Thus, in the case of a silicon semiconductor substrate, a nitrogen concentration of 5 x 10 ¹⁴ to 1 x 10 ¹⁶ atoms / cm ³ or 5 x 10 ¹⁸ to 1.5 x 10 ¹⁹ atoms / cm ³ for the silicon melt at the time of towing. Control can also be easily performed.

In the present invention, when growing a silicon single crystal rod doped with nitrogen by the CZ method or the magnetic field or CZ method, the oxygen concentration contained in the single crystal rod is in the range of 6.5 × 10 ¹⁷ to 1 × 10 ¹⁸ atoms / cm ³ . It is desirable to control. The method of lowering the oxygen concentration contained in the above range in the case of growing a silicon single crystal rod may be in accordance with a conventionally accepted method. For example, the oxygen concentration range can be simply set by means of decreasing the crucible rotation speed, increasing the flow rate of the introduced gas, lowering the atmospheric pressure, adjusting the temperature distribution of the silicon melt and convection.

In the present invention, in the case of growing a silicon single crystal rod doped with nitrogen by the CZ method or the magnetic field application CZ method, the cooling temperature when passing through the temperature range of 1100 ° C during crystal growth is set to 1 to 15 ° C / min. It is desirable to control. In practice, in order to realize such crystal manufacturing conditions, it is possible to carry out by a method of increasing or decreasing the growth rate of the crystal by adjusting the pulling speed of the crystal. Alternatively, a water cooling ring to surround the crystal at a predetermined position on the melt surface or a device capable of cooling the crystal by blowing the crystal into the chamber of the silicon single crystal device by an arbitrary cooling rate by the CZ method or the magnetic field applying CZ method. It may be applied to a method such as arranging. In this case, the cooling method and the pulling speed of the crystal can be adjusted to fall within the cooling rate range.

In such a CZ method or a magnetic field applying CZ method, a silicon single crystal rod can be obtained in which a desired concentration of nitrogen is doped, containing a desired concentration of oxygen, and crystal-installed at a desired cooling rate. The silicon single crystal rod is sliced with a cutting device such as an internally peripheral slicer or a wire saw according to a conventional method, and then, into a silicon single crystal wafer via a process such as chamfering, lapping, etching, and polishing. Processing.

Of course, these processes are cited for illustrative purposes, and the adoption of various other processes such as cleaning may also be considered. In addition, the process is suitably changed and used according to the purpose of change of a process sequence, a part omission, and the like.

Then, the silicon single crystal wafer thus obtained is subjected to heat treatment such as subsequent gettering heat treatment and / or heat treatment for device fabrication, so that the defect-free region of the oxygen precipitate crystal defect is defined as Oi DZ, and the void-free region having a size of 0.11 µm or more is obtained. When set to COP DZ,

(Formula 7)

(Oi DZ)-(COP DZ) 10 μm

Satisfies the relational formula and a silicon semiconductor having an oxygen precipitate crystal defect of 5 × 10 ⁸ / cm 3 or more, preferably 1 × 10 ⁹ to 1 × 10 ¹⁰ / cm 3.

In this case, the value of Oi DZ (oxygen precipitate free layer) is the depth of defect free layer (DZ) of the measurement result by the BMD analyzer (MO4), and the oxygen precipitate defect in the volume portion is determined through a 10% ND filter as a measurement condition. The depth which is 30% of the density is made into the defect free layer of oxygen precipitate defect (Oi DZ).

In the present invention, the upper limit of the maximum void volume of the silicon semiconductor substrate before heat treatment is defined by (Formula 2) and (Formula 3), but in the embodiment, the void volume is defined by the OPP (infrared interference method) maximum signal. It is also calculated in strength.

It is difficult to obtain the void volume by TEM in terms of cost and time, so it is clear that the relationship between the maximum void volume and OPP maximum signal strength among evaluation weights obtained by TEM observation in order to confirm whether the void volume is actually a predetermined void volume in the future. It was made.

The formula for calculating the void volume at the OPP maximum signal strength is based on the case of cooling rate of 1 ℃ / minute or more and less than 3 ℃ / minute, 3 ℃ / minute or more and less than 5 ℃ / minute, or more than 5 ℃ / minute and nitrogen concentration. The following changes have been confirmed in agreement between the measurement of void volume by TEM observation and the maximum signal strength of OPP.

As a result, the cooling rate is 5 ° C / min or more, and the nitrogen concentration of the silicon semiconductor substrate before the heat treatment is less than 5 x 10 ¹⁴ atoms / cm 3 or the cooling rate is 1 ° C / min or more and less than 3 ° C / min and nitrogen If the concentration is less than 2 x 10 ¹⁴ atoms / cm 3,

(Equation 8)

Void volume (nm ³ ) = 110000 × (OPP maximum signal strength) ^1.1

Is displayed.

Silicon before heat treatment at a cooling rate of 5 ° C / min or more and a nitrogen concentration in the silicon semiconductor substrate before heat treatment of 5 × 10 ¹⁴ or more and 1 × 10 ¹⁶ atoms / cm 3 or less or a cooling rate of 3 ° C / minute or more and less than 5 ° C / minute The nitrogen concentration of the semiconductor substrate is 2 × 10 ¹⁴ or more, but less than 2 × 10 ⁶ atoms / cm 3, or the cooling rate is 1 ° C./minute or more and less than 3 ° C./minute, and the nitrogen concentration of the silicon semiconductor substrate before heat treatment is 2 × 10 ¹⁴ or more. If less than 1 x 10 ¹⁵ atoms / cm 3

(Formula 9)

Void volume (nm ³ ) = 20000 × (OPP maximum signal strength) ^1.6 .

Silicon substrate before heat treatment at a cooling rate of 1 ° C./min and less than 3 ° C./minute, and nitrogen concentration of the silicon wafer before heat treatment at 1 × 10 ¹⁵ atoms / cm 3 or more, or a cooling rate of 3 ° C./minute or more and less than 5 ° C./minute. When the nitrogen concentration of 2 × 10 ¹⁵ atoms / cm 3 or more and 1 × 10 ¹⁶ atoms / cm 3 or less

(Formula 10)

Void volume (nm ³ ) = 110 × (OPP maximum signal strength) ^3.6 .

By using this relational expression, it is possible to obtain the maximum size of the void-based defects of the silicon semiconductor substrate when nitrogen is added, and confirm that the silicon semiconductor substrate manufactured before the heat treatment is controlled to the size of the void-based defects defined in the present invention. Can be.

In the embodiment, the maximum void volume of the measuring wafer obtained from the maximum signal intensity of OPP is approximately equal to the value calculated by applying the cooling rate and the nitrogen concentration described in this example by using the following equations (2) and (3). It was shown that the formula is limited to 100000 nm ³ and 150000 nm ³ or less in (Formula 2) and (Formula 3), respectively, while in the comparative example, it was found that the void volume was larger than the above-mentioned value. In order to obtain a silicon semiconductor substrate that satisfies the formula (1), it is shown that the cooling rate and the nitrogen concentration are required to be within the scope of the present invention.

In addition, the silicon semiconductor substrate according to the present invention forms a small oxygen precipitate defect such that segregated nitrogen cannot be measured by the BMD analyzer, so that the defect free layer on the surface is reliably secured at a depth of 5 µm or more on the surface. In nitrogen analysis by differential ion mass spectrometry (SIMS), it is preferable to provide a local enrichment part by nitrogen segregation which shows a signal intensity of at least twice the average signal intensity.

In addition, the silicon semiconductor substrate according to the present invention has a nitrogen concentration of 5 x 10 ¹⁴ atoms / cm 3 to 1 x 10 ¹⁶ atoms / cm 3, and the silicon semiconductor substrate is exemplified by hydrogen, nitrogen, argon, helium, and the like in a non-oxidizing atmosphere. After heat treatment in an atmosphere of one kind or two or more kinds of gas, the oxygen concentration of 1 占 퐉 depth at the surface of the substrate center is 7 x 10 ¹⁶ atoms / cm 3 or less, and for the above reason, In nitrogen analysis by secondary ion mass spectrometry (SIMS) at depth, it is also preferred to have a local enrichment by nitrogen segregation which exhibits a signal intensity of at least twice the average signal intensity. The reason for determining the upper limit of the nitrogen concentration of 1 × 10 ¹⁶ atoms / ㎤ is to avoid that a fear that, when the crystallization exceeds the nitrogen concentration is 1 × 10 ¹⁶ atoms / ㎤, pulling a silicon single crystal ingot.

As described above, the present invention is characterized in that an oxygen precipitate based defect, which is a gettering site, can be formed directly under the defect while controlling the depth of the defect-free region of the void crystal defect, which is a device active layer, so as to satisfy the following equation. It can be controlled.

(Equation 11)

BMD density 5 × 10 ¹⁴ / cm 3 and

(Oi-DZ)-(COP DZ) 10 μm

Silicon semiconductor substrates with such physical properties have 5 × 10 ¹⁷ to 1.5 × 10 ¹⁹ atoms / cm 3 when the cooling rate during ingot traction is 5 ° C./minute or more, and the cooling rate is less than 5 ° C./minute to 1 ° C./minute or more. In this case, a silicon semiconductor substrate obtained from a silicon single crystal grown by a CZ method or a magnetic field applied CZ method using a melt containing nitrogen of 1 x 10 ¹⁸ to 1.5 x 10 ¹⁹ atoms / cm 3 is preferably at least 1150 DEG C or higher. Preferably it is prepared by heat treatment in the non-oxidizing atmosphere for 1 hour or more at a temperature of 1200 ~ 1250 ℃.

In order to reliably realize the silicon semiconductor substrate according to the present invention, the CZ method or the magnetic field applying CZ method using a silicon melt containing nitrogen of 5 x 10 ¹⁷ atoms / cm 3 to 1.5 x 10 ¹⁹ atoms / cm 3 The maximum void volume at which the cooling rate at 1100 ° C. at the time of towing is 5 ° C./min or more, preferably 5 to 15 ° C./min is the nitrogen concentration of the silicon substrate before heat treatment at Natoms / cm 3 and 1100 ° C. at the time of towing. When the cooling rate at the temperature range of

(Formula 12)

8620000 × (CR) ^-1.4 × EXP (-3.3E-15 × [N]) 100000 nm ³

In the case of a silicon semiconductor substrate obtained at a cooling rate and a nitrogen concentration satisfying the relational expression shown in Fig. 1, at least 1 hour at a maximum achieved temperature of 1150 ° C or higher, preferably at least 0.5 hour at a temperature of 1200 to 1250 ° C, preferably 1 to 1 ° C. It is preferable to manufacture by heat-processing in non-oxidizing atmosphere for 2 hours.

In addition, when the cooling rate is slowed to less than 5 ° C / min, the void-based defects become large, so that a larger amount of nitrogen is required to reduce the voids. By diffusion, the heat treatment temperature is preferably higher. Therefore, in order to reliably obtain the silicon semiconductor substrate of claim 1 with high productivity, the CZ method or the magnetic field is applied using a silicon melt containing 1 x 10 ¹⁸ atoms / cm 3 to 1.5 x 10 ¹⁹ atoms / cm 3 of nitrogen. The maximum void volume of a silicon semiconductor substrate grown at a cooling rate of less than 1 ° C./min, preferably 3 to 5 ° C./min, by CZ method is a nitrogen concentration of Natoms / cm 3 before the heat treatment, When the cooling rate when passing through the temperature range is CR ℃ / min.

(Equation 13)

8620000 × (CR) ^-1.4 × EXP (-3.3E-15 × [N]) 150000 nm ³

The silicon semiconductor substrate obtained at the cooling rate and the nitrogen concentration satisfying the relational expression is heat-treated in a non-oxidizing atmosphere for 1 hour or more, preferably 1 to 2 hours at a temperature of at least 1200 ° C, preferably at 1200 to 1250 ° C. It is preferable to manufacture by making.

In the silicon semiconductor substrate produced by the manufacturing method of the present invention, the oxygen concentration of 1 占 퐉 depth from the surface of the wafer is 7 x 10 ¹⁶ atoms / cm 3 or less, and COP DZ is ensured at 5 占 퐉 or more, and the gettering of impurities A silicon semiconductor substrate is produced which is excellent and satisfies the relational expression (1).

(Example)

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited to these examples.

By the CZ method, polycrystalline silicon was loaded as a raw material into a 18-inch quartz crucible for a 6-inch diameter crystal pulley and a 22-inch quartz crucible for a 8-inch diameter crystal pull, and as shown in Table 1, 6-inch diameter and An 8-inch P-type, azimuth <100>, and a silicon single crystal rod having a resistivity of 8.5 to 11.5 Ω · cm were prepared by changing the conditions of nitrogen concentration, oxygen concentration, average SL, and cooling rate.

The control of the nitrogen dope amount was carried out by putting a silicon wafer having a predetermined amount of silicon nitride film in the raw material in advance.

Control of the oxygen concentration was carried out by controlling the crucible rotation during towing. The cooling rate was controlled by changing the pulling speed of the single crystal rods and changing the growth rate of the crystals. The measured value of the obtained silicon single crystal rod is as shown in Table 1.

The silicon single crystal mirror surface obtained by stripping, chamfering, lapping, etching, and mirror polishing by using a wire saw from the thus obtained single crystal was almost the same except for the amount of nitrogen doping, new concentration, and cooling rate. A plurality of wafers were each produced.

The gettering heat treatment was performed on the silicon single crystal wafer thus obtained. In this case, the gettering heat treatment is performed in an atmosphere formed of 20 vol.% Hydrogen and 80 vol.% Argon. The temperature rising rate is 8 ° C / min in the temperature range of 800 to 1000 ° C and 4 ° C / min in the temperature range of 1000 to 1100 ° C. Temperature increase rate, the temperature increase rate of 1 ° C./min in the temperature range of 1100 to 1150 ° C., the temperature increase rate of 1 ° C./min in the temperature range of 1150 to 1200 ° C., and the maximum achieved temperature is 4 hours or 8 hours at 1150 ° C. The fats and oils are maintained at 30 minutes for 2 hours when the temperature is raised to 1200 ° C. After holding, the temperature reduction rate of 1 ° C./min in the temperature range of 1200 to 1150 ° C., the temperature reduction rate of 1 ° C./min in the temperature range of 1150 to 1100 ° C., and the temperature drop rate of 4 ° C./min in the temperature range of 1100 to 800 ° C. It carried out by cooling. In the case of the heat treatment, the non-oxidizing atmosphere was the same even if the ratio of argon and hydrogen vol.% Was changed, and at the extreme, it was not damaged even at 100 vol.% Of argon or 100 vol.% Of hydrogen.

Subsequently, the defect free layer depth of these silicon single crystal wafers was evaluated. The wafer which changed the removal amount on the surface was prepared. Then, the fine COP is visualized by washing the wafer with an SC-1 mixture (a mixed solution of ammonia water (NH ₄ OH), hydrogen peroxide solution (H ₂ O ₂ ), and ultrapure water 1: 1: 20) at a temperature of about 80 ° C. for 1 hour. The surface of the wafer was measured using a SP1 particle measuring apparatus manufactured by KLA / Tencor Co., Ltd., and the COP number was counted for COP (Crystal Originated Particle) having a size of 0.11 µm or more.

The washing was repeated 10 times with the SC-1 mixture, and the COP volume density was calculated by subtracting the increase in the COP number measured after washing 10 times from the COP water before washing by the volume removed by etching with the SC-1 mixture. . In addition, the polishing removal thickness by repolishing was performed to the depth of 1, 3, 5, 7, 12 micrometers.

In addition, about the thickness of a defect-free layer, the oxide film breakdown voltage quality was evaluated about the wafer which changed the removal amount on the surface similarly to the above. The dielectric breakdown voltage quality was obtained by C mode yield of TZDB (Time Zero Dielectric Breakdown), in detail, an in-doped polysilicon electrode (oxide thickness of 25 nm, electrode area of 20 mm2), and the dielectric breakdown value evaluated at a determination current of 100 mA / cm 2. A good product having an electric field of 11 mA / cm or more was regarded as a good product, and a good yield was examined for all the electrodes in the wafer surface.

In addition, in order to investigate the oxygen precipitate defect density and Oi Dz, a heat treatment similar to the device heat treatment was applied to the silicon single crystal wafer of the present invention. The heat treatment was accomplished by subjecting the silicon single crystal wafer to a nitrogen atmosphere for 4 hours at 8000 ° C., followed by an oxidation heat treatment at 1000 ° C. for 16 hours.

In addition, the size of the defects with the maximum signal strength among the internal microdefects of the pulled and mirrored silicon single crystal wafer before heat treatment was evaluated. The internal microdefect density was measured by the OPP (Optical Precipitate Prpfiler) method, and the OPP method is a normalski-type microdispersive microscope. First, the laser tube emitted from the light source is separated into two straight orthogonal beams of two orthogonal 90 ° phases in the polarizing prism, and incident on the wafer mirror surface side. At this time, when one beam crosses the defect, a phase shift occurs, and a phase difference with the other beam occurs.

After the beam passes through the backside of the wafer, defects are detected by detecting the phase difference with a polarization analyzer.

The measurement results thus obtained were shown in Tables 2 to 6.

In the evaluation of the defect free layer depth, the COP number is evaluated by repeated washing with the SC-1 mixture, and the COP volume density in the wafer surface is 2 × 10 ⁵ pieces / cm 3 or less. The depth by which the yield rate satisfies 90% or more by evaluation by oxide film breakdown voltage (TZDB) is evaluated as a defect free layer.

Here, the data of Table 2 and Table 3 is an embodiment of the present invention having a diameter of 6 inches and is a silicon semiconductor substrate satisfying Claims 1 and 2, and at the same time satisfying the manufacturing conditions of paragraphs 3 to 5. That is, the cooling rate is 5 ° C./min or more, the nitrogen concentration is 5 × 10 ¹⁴ atoms / cm 3 or more, and the heat treatment is performed for 1 hour or more at a temperature of 1150 ° C. or more in a non-oxidizing atmosphere. The oxygen concentration satisfies the condition of 7 × 10 ¹⁷ atoms / cm 3 or less in the measurement by SIMS.

In the present embodiment, the annealing condition is 1200 占 폚 for 0 hours, and the elevated temperature rise time at 1150 占 폚 to 1200 占 폚 is 100 minutes in total (elevation rate in the non-temperature range is 1 占 폚 / min), It satisfies the conditions of 1 hour or more at 1150 degreeC or more which is the manufacturing conditions of this invention.

The calculated void volume shown in the table is the maximum void volume of the silicon semiconductor substrate before heat treatment determined from the formula on the left side of Equation 2 by the cooling rate and the nitrogen concentration shown in each example. In addition, the OPP calculation void volume in a table | surface is the value calculated | required by Formula (8)-(10) from the maximum signal intensity by OPP measurement. The void volume satisfies the maximum allowable void volume 100000 nm ³ or less shown on the left side of (Formula 2), similar to the maximum void volume (calculated void volume in the table) calculated on the left side of Equation 2 above, and OPP It is confirmed that the silicon semiconductor substrate before heat treatment obtained by the evaluation by is in the range specified in the present invention. In addition, the maximum signal strength obtained from OPP measurements is obtained only by digitized measurements on the measuring device. For this reason, the void volume obtained from the OPP maximum signal strength and the void volume obtained from Equation 2 are not necessarily the same value.

The data in Table 4 relates to a product having a diameter of 6 inches according to a comparative example which does not satisfy the conditions of the silicon semiconductor substrate of the present invention. They are not always satisfied below 5 x 10 ⁸ pieces / cm 3 as the oxygen precipitate crystal defects described in claim 1 are mainly in the concentration of nitrogen outside the range of the present invention under the manufacturing conditions of claims 3 to 5, (Oi DZ)- (COP DZ) The relationship of 10 mu m is not satisfied.

In addition, the data in Table 5 relates to a product having a diameter of 8 inches according to the embodiment of claim 6 of the present invention, these products relates to a silicon semiconductor substrate satisfying claim 1. That is, the nitrogen concentration of the silicon semiconductor substrate before the heat treatment at a cooling rate of 1 ° C./min or less and 5 ° C./min or less is 1 × 10 ¹⁵ atoms / cm 3 or more, and the heat treatment is performed at a temperature of 1200 ° C. or more for 1 hour or more in a non-oxidizing atmosphere. After the heat treatment, the oxygen concentration at a depth of 1 占 퐉 from the surface satisfies the condition of 7 x 10 ¹⁷ atoms / cm 3 or less in the measurement by SIMS.

The calculated void volume of Table 5 is the maximum void volume of the silicon semiconductor substrate before heat treatment determined from the formula of the left side of Equation 3 by the cooling rate and the nitrogen concentration shown in each example.

The OPP calculation void volume in the table is obtained by substituting the maximum signal intensity from the OPP measurement into the equation (Eq. 8) to (Eq. 10), and the calculated void volume and the OPP void volume are shown in Equation (3). The maximum allowable void volume of the left side is 150000 nm ³ or less.

The data in Table 6 relates to a product according to a comparative example which does not satisfy the conditions of the silicon semiconductor substrate of claim 6, which mainly has a diameter of 8 inches. They do not always satisfy the 5 × 10 ⁸ defects / cm 3, which is the oxygen precipitate crystal defect described in claim 1, because the nitrogen concentration is mainly outside the scope of the present invention under the manufacturing conditions of claim 6, and (Oi DZ)-(COP DZ) The relationship of 10 mu m is not satisfied.

As described above, the silicon semiconductor substrate according to the present invention has a structure in which a high density of oxygen precipitate defects, which become gettering sites, is formed directly below the defect-free regions of void-based defects. It is an invention that can control the density of oxygen precipitate defects and their depth of occurrence. This technique is made possible by limiting the range of nitrogen concentration and cooling rate of the silicon semiconductor substrate before heat treatment to the scope of the present invention.

Claims (6)

In a substrate heat-treated with a silicon semiconductor substrate obtained from a silicon single crystal grown by the Czochralski method or the magnetic field-applied Czochralski method, the void region of the oxygen precipitate crystal defect is defined as Oi DZ and has a void type of 0.11 탆 or more. When the area without defects is COP DZ, (Formula 1) (Oi DZ)-(COP DZ) 10 μm And a silicon oxide crystal defect of at least 5 x 10 ⁸ atoms / cm 3. 2. A silicon according to claim 1, characterized in that it has a localized thickening portion by nitrogen segregation which exhibits a signal intensity of at least 5 µm from the surface and at least twice the average signal intensity in nitrogen analysis by secondary ion mass spectrometry (SIMS). Semiconductor substrate. The oxygen concentration of 1 占 퐉 deep at the surface at the center of the substrate after heat treatment in a non-oxidizing atmosphere of a silicon semiconductor substrate having a nitrogen concentration of 5 x 10 ¹⁴ atoms / cm 3 or more and 1.5 x 10 ¹⁶ atoms / cm 3 or less. It has a localized thickening part by nitrogen segregation that is 7 × 10 ¹⁶ atoms / cm 3 or less and has a depth of 5 µm or more on the surface and shows a signal intensity of more than twice the average signal intensity in nitrogen analysis by secondary ion mass spectrometry (SIMS). Method for producing a silicon semiconductor substrate, characterized in that. The silicon single crystal according to claim 1, wherein a silicon melt containing at least 5 x 10 ¹⁷ atoms / cm 3 and at most 1.5 x 10 ¹⁹ atoms / cm 3 is grown by Czochralski method or magnetic field applied Czochralski method. The silicon semiconductor substrate thus obtained was heat-treated at a temperature of at least 1150 ° C. for at least 1 hour in a non-oxidizing atmosphere so that an oxygen concentration of 1 μm deep at the surface at the center of the substrate was 7 × 10 ¹⁶ atoms / cm 3 or less, and 5 at the surface. A method for producing a silicon semiconductor substrate, characterized by having a localized enrichment portion by nitrogen segregation which exhibits a signal intensity of more than twice the average signal intensity in nitrogen analysis by secondary ion mass spectrometry (SIMS) at a depth of not less than µm. The method according to claim 1, wherein the silicon melt containing nitrogen of 5 x 10 ¹⁷ atoms / cm 3 or more and 1.5 x 10 ¹⁹ atoms / cm 3 or less is used for the towing by the Czochralski method or the magnetic field-applied Czochralski method. A silicon semiconductor substrate obtained from a silicon single crystal with a cooling rate of 5 ° C./min or more when passing through a temperature range of 1100 ° C. during the process, and the nitrogen concentration of the silicon substrate before the heat treatment is Natoms / cm 3, The cooling rate at the time of passage is the maximum void volume of the void system defect at CR ° C / min. (Formula 2) 8620000 × (CR) ^-1.4 × EXP (-3.3E-15 × [N]) 100000 nm ³ A method of manufacturing a silicon semiconductor substrate, wherein the silicon semiconductor substrate obtained at a cooling rate and nitrogen concentration satisfying the relational expression is heat-treated in a non-oxidizing atmosphere for at least 1 hour at a temperature of at least 1150 ° C. Temperature range of 1100 ° C when towed by the Czochralski method or the magnetic field-applied Czochralski method using silicon melt containing nitrogen of 1 × 10 ¹⁸ atoms / cm 3 or more and 1.5 × 10 ¹⁹ atoms / cm 3 or less A silicon semiconductor substrate obtained from a silicon single crystal grown at a cooling rate of 1 ° C / minute or more and less than 5 ° C / minute when passing through it, and having a temperature range of 1100 ° C when the nitrogen concentration of the silicon substrate before heat treatment is Natoms / cm 3 or towed. The maximum void volume of the void system defects when the cooling rate at the (Formula 3) 8620000 × (CR) -1.4 × EXP (-3.3E-15 × [N] 150000 nm ³ A method of manufacturing a silicon semiconductor substrate, wherein the silicon semiconductor substrate obtained at a cooling rate and nitrogen concentration satisfying the relational expression is heat-treated at a temperature of at least 1200 ° C. for at least 1 hour in a non-oxidizing atmosphere.